From geologic puzzles of deep time to unsolved crimes of the 20th century, here are 15 of history’s greatest mysteries—most of which remained unsolved to this day. 1. Where is Cleopatra’s tomb?

Our all-time favorites include whodunits, horror novels, police procedurals, and more. If you have a crime, a question, and someone looking for answers, then you've got a mystery.

Recently, there was news that there might be some development to the disappearance of the ill-fated Malaysia Airlines Flight MH370, that literally vanished into thin air in 2009. Dr. Vincent Lyne ...

As discussion of time travel becomes less of a scientific taboo, the chances of building a time machine improve. It isn't beyond the realm of reason that by the end of the 21st century we could be ...

The 50 Best Mysteries of All Time If you have a crime, a question, and someone looking for answers, then you've got a mystery. Our all-time favorites include whodunits, horror novels, police ...

Dark energy, early supermassive black holes, the nature of dark matter, and the blazing heat of the sun's atmosphere are just some of the space mysteries that confound scientists.